Shouting Paula Bennett and Gerry Brownlee tickets to a Bon Jovi concert is business as usual for Westpac and not part of a campaign to curry favour to help retain a large lucrative Government contract, the bank says.

The Greens yesterday raised concerns that senior ministers and their staff "continue to regularly accept generous corporate hospitality" from the bank at a time when the Government's master banking contract was under review.

Westpac has held the contract - believed to the biggest banking contract in New Zealand - for about 20 years but Finance Minister Bill English late last year confirmed the Government was considering the status of that arrangement.

"Ministers accepting personal gifts from Westpac creates a potential conflict of interest as the Government is actively considering retendering part, if not all, of the banking master contract," said co-leader Russel Norman.

The Government's response to a series of written questions from the Greens reveal ministers and their staff have enjoyed box seats at the Wellington Rugby Sevens tournament, dinner at Wellington's upmarket White House restaurant and tickets to rock concerts.

Mr Brownlee and Ms Bennett were Westpac NZ chief executive George Frazis' guests when Bon Jovi played in Wellington last year.

Dr Norman said there was "an important difference between doing business in a friendly way and using money to buy access to power".

A spokesman for Westpac said the bank's hospitality programme, "to build and maintain relationships" meant that invitations were extended "to a broad range of key stakeholders including members of both sides of the House, "without prejudice or expectation".

The spokesman said the bank had not extended any more hospitality to ministers or their staff since becoming aware of the procurement process for the banking contract.

A spokesman for Mr English said officials were doing initial work on that process which would be "the first time in over 20 years the Government's master banking contract has been opened to a competitive process".

Prime Minister John Key said it was "a healthy thing" the contract was being opened up to competition.